Chocolate chips are made with wax which helps them keep their shape.... it really dosent do much for ganache though. If you use real chocolate you will notice a difference in your ganache. It dosent look and feel.... runny I guess is the only way to describe it.... HTH

Sometimes the chips have a coating on them to help them keep their shape - good for cookies, not so good for melting. Also some people prefer to finely chop the chocolate so it melts easier in the cream.

I find it a pain to chop the chocolate so I use a couverture that comes in small pieces (slightly bigger than chips) - rarely have a problem getting them to melt in the cream, if it doesn't melt completely I just put my bowl over a pan of boiling water and stir until smooth.